Prolactin heterogeneity in the serum and milk during lactation

Prolactin heterogeneity in serum and milk were separated using Sephadex G-100. Three components were present in serum from lactating women with the following proportions: “void volume” -13.4%, “big” - 26.4%, and “little” - 60.3%. Milk from the same subjects did not contain “big” prolactin. Over 90% of the prolactin found in milk was “little” prolactin. The “little” prolactin in milk may not be similar to the “little” prolactin in the serum.